Electronic devices of the generic type, so-called data loggers, are used wherever long-term recording of measurement parameters is to be done without the continuous presence of monitoring personnel on site. Thus data loggers are used mainly in field tests, in the monitoring of transport, i.e. in the monitoring of acceleration, humidity and climate values in trucking or rail transport, for recording humidity and temperature values in warehouses, in the pharmaceutical and food industry, for fault analysis of systems, for example for recording of voltage fluctuations in or on a system, for monitoring and alerting in production processes and in quality studies, in research, development and education. Data loggers are also used for recording and monitoring of measurement data in the hobby domain, for example in model aircraft.
The measurement data recorded and stored over a longer time interval can if necessary be further processed, graphically displayed and statistically evaluated for documentation. In addition to measurement data, data loggers often also record all events, such as for example a battery change, operator intervention or changing of a memory card, which occur on the device during a monitoring interval. Thus, these data loggers can meet an especially important criterion of the pharmaceutical, food and chemical industry which can abbreviate the audit trail. The measurement data recorded by the data logger and the data for the audit trail are filed in an internal hardware memory. For evaluation of all data, the data logger is ordinarily connected by cable to the data processing system, for example a PC, in order to read out the data. The readout of data can also take place via a cable-supported or also a cableless LAN or similar network. After reading out the data, they are processed with hardware-specific evaluation software in order to make them available in the form of tables and graphics and to prepare documents or reports. This form of evaluation results in that at any workplace at which the measurement data are to be displayed, the corresponding hardware-specific evaluation software is installed.
Data loggers are also known which are equipped with a display and thus make it possible to display tables and graphics on the display of the device to a limited extent. To do this, the recorded measurement data are further processed by an internal processor and conditioned for display on the display. The reading of the measurement data which are displayed over the hardware-internal display to a limited extent involves presence at the site of the data logger. Graphic or tabular display of the measurement data at one site remote from the location of the data logger is only possible when the data processing system present there, for example a PC, is equipped with the corresponding hardware-specific evaluation software. Other data loggers can be connected to a printer or plotter. For this purpose, in the connection to the additional output device, limited processing of the measurement data by the internal processor has been triggered. The conditioned data can then be printed out or plotted as a table or graphics. The printed table or graphics can be sent to a more remote location if necessary over long-distance transmission devices, for example fax. This detour via the paper form can, however, be time-consuming and often linked to qualitative problems in display. In these known data loggers, direct graphic or tabular display of the measurement data at a location remote from the location of the data logger is only possible when the data processing system present there, for example a PC, is equipped with the corresponding hardware-specific evaluation software.